package com.hqq.structure.flyweight;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;
import java.util.Vector;

/**
 * ConnectionPool
 * 享元模式
 * 主要目的是实现对象的共享，即共享池，当系统中对象多的时候可以减少内存的开销，通常与工厂模式一起使用
 * Created by heqianqian on 2017/3/11.
 */
public class ConnectionPool {
    private Vector<Connection> pool;

    /*公有属性*/
    private String url = "jdbc:mysql://localhost:3306/test";
    private String username = "root";
    private String password = "root";
    private String driverClassName = "com.mysql.jdbc.Driver";

    private int poolSize = 100;
    Connection connection = null;

    /*构造方法 做一些初始化工作*/
    private ConnectionPool() {
        pool = new Vector<>(poolSize);

        for (int i = 0; i < poolSize; i++) {
            try {
                Class.forName(driverClassName);
                connection = DriverManager.getConnection(url,username,password);
                pool.add(connection);
            } catch (ClassNotFoundException e) {
                e.printStackTrace();
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
    }

    /*返回连接到连接池*/
    public synchronized void release() {
        pool.add(connection);
    }

    /*返回连接池中的一个数据库连接*/
    public synchronized Connection getConnection() {
        if (pool.size() > 0) {
            Connection connection = pool.get(0);
            pool.remove(connection);
            return connection;
        } else {
            return null;
        }
    }
}





















